This uninhabited island was claimed by the US in 1857 for its guano. Mining took place between 1865 and 1898. The lighthouse, built in 1917, was shut down in 1996 and administration of Navassa Island transferred from the US Coast Guard to the Department of the Interior. A 1998 scientific expedition to the island described it as a unique preserve of Caribbean biodiversity; the following year it became a National Wildlife Refuge and annual scientific expeditions have continued.